A fire broke out in a closed cell in a Prison in the Western German City of Kleve, leaving an inmate and two prison officers seriously injured.
Six further employees and two more inmates were left with minor injuries from smoke inhalation, police and the director of the prison said.
They were released from hospital a short while later.
Prison director Udo Gansweidt told dpa that the cause of the fire was not clear.
The badly injured 26-year-old inmate, who was in a solitary cell as punishment for theft, was not yet fit for questioning.